<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button>点击</button>
    <script>
        const button = document.querySelector("button")
        function fn() {
            alert("hello javascript");
        }
        button.addEventListener("click", fn)
        // 移除事件监听
        button.removeEventListener("click", fn)
    </script>
</body>

</html>